1. Field of the invention
The present invention relates to a microwave dielectric composition and a preparing method therefor. More particularly, the present invention relates to a microwave dielectric composition superior in all dielectric constant, product of resonant frequency by quality coefficient and temperature-dependent coefficient of resonant frequency. Also, the present invention is concerned with a method for preparing such a microwave dielectric composition.
2. Description of the Prior Art
Today, various microwave dielectric compositions are used in high frequency integrated circuits or dielectric resonators. In addition, the exploitation for ever higher frequency in high frequency band has been continuous. Together with the availability of high frequency, the tendency toward simpleness, thinness, shortness and smallness in electromagnetic appliances, has made the demand for the microwave dielectric composition which is more improved in dielectric constant and quality coefficient.
To meet the demand, J. Kato et al. developed a microwave dielectric composition comprising lead oxide (PbO), calcium oxide (CaO) and zirconium oxide (ZrO.sub.2) through an oxide mixing technique, as reported in Jpn. J. Appl. Phsy. 30(9B) 2343(1991) and 32(9B) 4356(1993). The compositions are found to be superior in individual dielectric constant, temperature coefficient of resonant frequency and the product of quality coefficient by resonant frequency but not in all of the properties. Accordingly, the compositions of J. Kato et al. are not suitable for use in microwave dielectric appliances, in practice.